Answer to Question 1
D.
The relativistic factor depends on one over the square root of one minus the velocity squared over the speed of light squared, so as velocity approaches and passes the speed of light, the factor approaches infinity and then becomes imaginary.
Answer to Question 2
The speed of propagation of any wave through a medium depends most importantly on the medium itself. All observers measure the speed of light to be the same in inertial frames, and since both Samus and Ridley are in the same medium, they should measure the same speed of light.